Europe must step up urgently to improve its defence and make Nato "more European to maintain its strength", because the US has shaken the transatlantic relationship to its foundation, the EU's foreign policy chief has warned.

The US would remain Europe's partner and ally, Kaja Kallas told a defence conference, but no great power had ever "outsourced its survival and survived".

Tensions with the US escalated when President Donald Trump threatened to annexe Greenland, a semi-autonomous Danish territory.

Kallas's remarks came after Nato leader Mark Rutte prompted a backlash when he said European lawmakers should "keep on dreaming" if they thought Europe could defend itself without the US.

French Foreign Minister Jean-Noël Barrot reacted to the secretary general's comments on Tuesday by saying, "No, dear Mark Rutte. Europeans can and must take control of their security. Even the United States agrees. It's the European pillar of Nato."

Kaja Kallas said that under the Trump administration Europe was "no longer Washington's primary centre of gravity", and the continent needed to change the culture away from thinking as nations, and towards acting jointly as Europeans.

Washington's transition away from Europe "has been ongoing for a while", the EU foreign policy chief said, adding that it was structural, not temporary.

The 23 nations that were members of both the EU and Nato had a special responsibility to "sync our efforts, together with Nato". Like Barrot, she highlighted the importance of showing how a "distinct European pillar" would add value.

The recent US-European rift over Greenland has highlighted the "tectonic shift" in the relationship that Kallas referred to in her speech, with Trump threatening to impose tariffs on some of his closest European allies after they opposed his plans to take over the Arctic island.

Mark Rutte was credited last week with calming tensions between Trump and European leaders when the US president dropped his threat during talks with the Nato chief on the fringes of Davos. Trump said he was exploring a potential deal on Greenland, although no details have yet emerged.